WE SCAR NPAS issues

[voorhees -FWA-]

Hey all,

The rifle is a WE SCAR L Open Bolt with NPAS and a 355mm inner barrel running just propane mags.

I've got Claybank in a couple days and my NPAS decided it doesn't want to shoot below 440FPS anymore.
I get a range of 440FPS - 500FPS no matter where I adjust my NPAS too. I set it all the way closed, it chrono's @443FPS, I set it all the way open and it shoots @500FPS; anything in between varies from 440 - 500...
The unit and the nozzel are basically new, gamed it twice (a couple 45 minutes games about 5 mags worth of shooting) this season and it was fine.

I don't really want to run duster either as I will also be running Tornadoes and M203's...

Any ideas, other than get a new NPAS, greatly appreciated... thanks!

[pinksoda]

Same problem with mine shoots around that fps too either open or almost closed. i havnt gamed mine yet though i couldnt cuz its firing over 400. I notice the npas is not always straight its some times tilts a bit. I noticed that the npas dosent sit flat on the spring. Not sure if its the one causing it. What was the fps of your scar when you gamed it? I just bought mine last week.

[voorhees -FWA-]

Mine was 440 but we regulate joules not FPS and the limit is 1.6, mine was just over that at 1.76 with .28g but I still played it as a DMR (semi only, pistol in close quarter).

I took the nozzel apart and inspected the o-rings and everything seems fine, checked placement and the spring, cleaned and lubed everything and there's no change... still 440+ no matter where I adjust it too...

I have another NPAS in my 16, I'm going to swap nozzels and see if I can fall below 400 with that one, if not, I guess I will have to run duster, which is lame...

Any ideas at all will be helpful, thanks.

[Fox62]

If you guys are really desperate, you can always remove one loop from your floating valve (in this case NPAS) spring. Cut it right off. It'll get you to a perfectly gameable range.

Fox.

[pinksoda]

Will there be any side effects?

Ok, I was totally desperate to use this saturday. So I cut of the head(flat part) of the old valve and used glue gun to stick it to the head of the NPAS. I made sure that its on there so i rapped it together with the glue and made sure that theres a gap inside so the npas can move freely while the nozzle is separated. Some how first shot was 500 then couple more shots its gone down to 300 and pretty consistent too, around 290 - 300. If anything goes wrong I'll post it here. Also before i did this, i made sure i have all the replacement parts needed just in case if anything happens.

[Fox62]

Originally Posted by pinksoda

Will there be any side effects?

Ok, I was totally desperate to use this saturday. So I cut of the head(flat part) of the old valve and used glue gun to stick it to the head of the NPAS. I made sure that its on there so i rapped it together with the glue and made sure that theres a gap inside so the npas can move freely while the nozzle is separated. Some how first shot was 500 then couple more shots its gone down to 300 and pretty consistent too, around 290 - 300. If anything goes wrong I'll post it here. Also before i did this, i made sure i have all the replacement parts needed just in case if anything happens.

LOL that's a pretty desperate solution dude, I would had cut a loop. With only one loop, the effects should be similar to that of a lighter spring (which is the best solution honestly; no NPAS, just the stock valve, and fixed gameable power). The perfect scenario is one in which you try different springs until you get your gun in the desired output range. But I'd first try cutting a loop, I think it'll get you in the sweet spot.


Fox.

[pinksoda]

Originally Posted by Fox62

LOL that's a pretty desperate solution dude, I would had cut a loop. With only one loop, the effects should be similar to that of a lighter spring (which is the best solution honestly; no NPAS, just the stock valve, and fixed gameable power). The perfect scenario is one in which you try different springs until you get your gun in the desired output range. But I'd first try cutting a loop, I think it'll get you in the sweet spot.


Fox.

I did try cutting a loop same results even with the pistol spring. Decreasing the fps only works if the npas is away from the nozzle whole(where the gas enters) right? Even if i open the npas to the tip of its thread it still gave me 450+. Cutting a loop didnt help. the valve is still the same length as before. If there is a detailed explanation on how cutting a loop of the spring or replace it with a lighter spring would make a difference. i might have missed something when i was doing it.

[Fox62]

Originally Posted by pinksoda

I did try cutting a loop same results even with the pistol spring. Decreasing the fps only works if the npas is away from the nozzle whole(where the gas enters) right? Even if i open the npas to the tip of its thread it still gave me 450+. Cutting a loop didnt help. the valve is still the same length as before. If there is a detailed explanation on how cutting a loop of the spring or replace it with a lighter spring would make a difference. i might have missed something when i was doing it.

Could you please try everything with the stock valve? I hate the NPAS to be honest. In any case, the theory behind it is that a heavier spring will allow for more time the valve remains open, thus allowing for more gas to be used in propelling the BB, pretty basic, huh? A lighter and/or shorter spring will close faster, and have the gun use more gas on the blowback action.

Try a stock spring with the stock valve, then lighter spring/cut stock spring with it. You should experience at least SOME difference.


Fox.

[pinksoda]

Stock valve + stock spring with 1 loop cut = cqb fps(360)?
How much decrease on fps with lighter spring?
How much decrease on fps with 1 loop cut spring?

[HKGhost]

In order to lower the fps with an NPAS, you need to mod the nozzle (inner part). Pull the nozzle out, split it in half by removing the thin pin that's holding the two ends together. Inside you'll see a female side and a male side (male side has the tiny oring). You'll see two prongs that needs to be removed on the male side. After that, cut a notch in a cross configuration about 2mm deep. And that's it. Put everything back together and you can now lower the FPS down to 200fps. It's the same mod that's done to the WE M14 nozzle.

[Fox62]

Originally Posted by pinksoda

Stock valve + stock spring with 1 loop cut = cqb fps(360)?
How much decrease on fps with lighter spring?
How much decrease on fps with 1 loop cut spring?

It depends on the gun. I thought you had a Chrono. If you have the stock valve lying around start shootin' in different configurations.


Fox.